The present invention relates to a double row angular contact ball bearing having a one-piece inner ring and a one-piece outer ring and adapted for use mainly as an automobile wheel bearing.
Since this type of bearing has the advantages of reduced mounting man-hours, elimination of internal clearance adjusting operation, stability of quality after mounting, reduced size, reduction in weight, etc., recently a wheel bearing has been developed in which either one or both of inner and outer rings 2' and 1' are formed with flanges 16 and 17 as shown in FIG. 9. In the case of a bearing used with an automobile axle, the bearing is subjected to a thrust load, moment, etc., in addition to the usual radial load and consequently the bearing is required to have a capacity to withstand these loads and a long life. In particular, since large thrust load and moment are imposed on the balls in one of the raceway pairs during a turning, the load capacity of the balls in the raceway pair subjected to large loads must be increased. In addition, a difference is caused in the number of orbital revolutions between the balls in the two raceway pairs and it is necessary to ensure that the bearing conforms satisfactorily with the situation.
To meet these requirements, many improved bearings have been proposed including a Conrad-type ball bearing (Japanese Laid-Open Patent Application No. 47-5609) produced by making an outer ring and an inner ring eccentric, inserting balls into the crescent-shaped spaces formed by the raceway tracks of the outer and inner rings, bringing the outer and inner rings back onto the same axis to arrange the balls at equal spaces and then inserting a one-piece cage from the non-flanged side to hold in place the balls of the two raceway pairs, a bearing (Japanese Laid-Open Patent Application No. 50-109339) incorporating a one-piece cage having a complex shape and made from a special material to cope with the difference in the number of orbital revolutions between the two rows of balls and a bearing (Japanese Laid-Open Patent Application No. 53-71401) in which the number of balls inserted in one of two raceway pairs is greater than that of the other raceway pairs and an outer ring which has been preliminarily divided in a plane perpendicular to the axis is made into a one-piece outer ring by pins after the completion of the assemblage. However, these prior art bearings have the disadvantages of being insufficient in load capacity, being incapable of properly responding to the difference in the number of orbital revolutions, being difficult to manufacture, being difficult to maintain the desired processing accuracy and so on.
Still another type of bearing has been proposed (U.S. Pat. No. 3,532,401) in which balls of the second row of a lesser number of balls are inserted by tilting a one-piece outer ring and a one-piece inner ring with reference to each other and the bearing is so designed that a large number of balls is inserted in one of the raceway pairs in a maximum-type manner and that the inclination of the outer ring with respect to the inner ring is determined by inclining the outer ring against the axis passing through the center of one of the inserted maximum-type balls. As a result, while the ball forming the center of rotation of the outer ring is always held in contact with the bottom of the outer ring raceway track and the other balls move away from the outer ring raceway track as soon as the outer ring inclines in such a manner that the balls move away increasingly from the raceway track as the inclination of the outer ring increases, thus increasing the previously mentioned crescent shaped space, this has the effect of increasing the axial deviation of the positional relation between the other outer ring raceway track having no balls inserted and the inner ring raceway track, with the result that the number of balls inserted in the other outer ring raceway track becomes insufficient and the desired load capacity is not ensured, thus making the rated load of the bearing not necessarily satisfactory and failing to ensure a highly reliable life of the bearing on the whole.